The tstat sounds like it is not connecting the white and red terminals which is usually the heat cycle if it is a gas furnace if so to check I take tstat cover off and jump white terminal to red terminal this is the standard heat position the unit should fire the heat cycle if not a gas funace let me know what type of unit you have hope this helps

1 Suggested Answer

Hi,
A 6ya expert can help you resolve that issue over the phone in a minute or two.
Best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
The service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).click here to download the app (for users in the US for now) and get all the help you need. Good luck!

Tell us some more! Your answer needs to include more details to help people.You can't post answers that contain an email address.Please enter a valid email address.The email address entered is already associated to an account.Login to postPlease use English characters only.

What kind of water heater do you have?In any case, it sound like a plumber should check out system.

Do you have indirect heater that gets heat from central heating boiler?Most indirect/boiler combo heaters have control that is set to heat the water first.If water is not getting heated, then the control needs repair.

Do you have gas water heater with gas central heating?The central heater may be drawing so much gas from meter, that other gas appliances are unable to function. larger gas meter or gas line may be needed.Or if furnace and water heater vent on same chimney, the backflow from central heat could be affecting burner on water heater especially if water heater has electronic sensor that stop combustion if air quality is bad. Venting problems can lead to CO poisoning, and are a serious matter.

The Cold Air Return is really the Return Air. The Purpose of the Return
air duct is to pull the cooled or heated air back to the furnace. It then
filters the air before getting cooled or heated again.

This is what controls the thermostat, which starts and stops the unit. In
the end this is how your air stays conditioned. In some states it is
required by law that a 4-6inch fresh air vent be tied into the return air
duct. Everytime the furnace fan comes on, it pulls in fresh air from
the outdoors.

Check the pilot light.Older standing pilot systems use thermocouples to verify the pilot is burning before the gas valve opens.If the pilot wont stay lit replace the thermocouple. Newer systems light the pilot.On a call for heat the igniter lights the pilot. When the heat is verified the gas valve opens . Some systems use an circuit board with flashing led lights to help troubleshooting.

Sounds like it may have lost power. Check the breaker and the fuse at the furnace. If they are all in the on position and working then it sounds like you may need a technician. If the display is blank on the thermostat you may also want to replace the batteries.